Audio/visual presentations often employ light projection systems which allow modulation of a light source and projection of the modulated light source onto a screen. In a typical prior art projection system, a light source provides light along an optical path to a light modulator where the light is modulated in accordance with the computer-generated presentation and continues along the optical path where it is projected onto a screen.
One implementation of a prior art light projection system is achieved by utilizing a digital micromirror from Texas Instruments Incorporated, like the Lite Pro 620 projector from InFocus Systems, Inc. of Wilsonville, Oreg. The digital micromirror is an array of individual mirrors controlled by a computer to modulate light from a light source, with each mirror controlling an on-screen pixel. In one embodiment, the pixel is turned ON or OFF depending on the orientation of the corresponding mirror. An ON condition occurs when the light from the source is directed onto the screen, with an OFF condition being when the light is directed away from the screen.
Once having generated on-screen material, it is useful to utilize a pointing device to select particular areas, and even pixels, on the screen. One prior art pointing device is available as the Cyclops laser pointer. While laser pointers have been available for many years to designate or call attention to on-screen material, it is oftentimes useful to change the on-screen material by selecting a particular on-screen icon or other indicia and by so doing cause the computer to change the displayed information. Thus, when using a computer driven display, it is oftentimes desirable to provide a cursor on the display and to click on a portion of the display as if by using a mouse so as to have the computer change the presentation to the selected material. As a result, it is desirable to have a device which can both illuminate a selected portion of the screen to highlight some text or select an icon and have the computer-generated display respond to this selection with the presentation of new material.